Queues are used for bandwidth management and prioritize traffic (QOS):
1. Limit data rate for certain IP addresses, subnets, protocols, ports, and other parameters
2. Limit peer-to-peer traffic
3. Prioritize some packet flows over others
4. Configure traffic bursts for faster web browsing
5. Apply different limits based on time
6. Share available traffic among users equally, or depending on the load of the channel
Queue implementation in MikroTik RouterOS is based on Hierarchical Token Bucket (HTB). HTB allows to create hierarchical queue structure and determine relations between queues.